Alcoholic fermented beverages, for example beers, have a tendency to produce haze during storage and a number of products and processes are known for the removal of haze forming constituents. The haze or turbidity in beer is removable by filtration but a further haze or turbidity can develop on storage. This haze would therefore become apparent only at the stage when the beverage is being prepared for consumption when removal would not be possible. It is therefore desirable to remove during production both the haze developed during the fermentation processes or on standing prior to final processing together with the haze precursors which may develop haze during storage. Materials used for treating the beverage must not remove the components which are essential to the character i.e. body and flavour, of the beer or the head forming components and colouring.
It is believed the haze originates from the presence of certain proteins and any treatment must be selective in removing only those protein species which are responsible for haze formation while leaving other beneficial protein species as constituents of the product sold.
Although the present invention is directed to the treatment of beers, which term includes ales, lagers and stouts, it is applicable to other fermented liquids which are liable to generate haze on storage. Various materials such as bentonites, active carbon, polyvinyl pyrrolidone and silicas have previously been proposed for this purpose and are used commercially, but silicas are preferred because they are more selective in removing the protein species responsible for haze formation without impairing the desired properties of the beverage.